Sphceraphides of Phanerogamia. 227 



prefix or affix for other forms of crystals. Among Phanero- 

 gamia they occur most commonly in a more or less globular 

 congeries^ either naked or within a cell; and these I shall in 

 future call Sphseraphides [crtpalpa, sphcera, and pa<l>l<i, k pairrco, 

 as above). 



Size and Form of the Spharaphides. — Common sizes of the 

 sphseraphides are ^-jij-oth and o^'^^j th ; but they often vary from 

 -e-oVoth to 1 o'o o ^^ of ^^ i^ch in diameter, and are occasionally 

 still larger. They are of a round form, and often appear as the 

 nucleus of a cell, and sometimes without any visible cell-wall. 

 The diameter of the individual crystals is frequently about 

 o o th, varying from 3auou th to TirVoth of an inch. Of these 

 it is usually impossible to define the forms exactly, on account 

 both of their minuteness and of the difficulty there is in getting 

 them detached so as to roll about and display their shapes in the 

 microscopic field of vision. We can generally see that they are 

 more or less crystalline, and sometimes that they belong either 

 to the octahedral or prismatic system. But whether the forms 

 are primitive or secondary is not easy to determine ; and, indeed, 

 the angles and edges are often more or less rounded off, or other- 

 wise so far modified as to make it difficult, without a careful 

 examination, to recognize them as crystals. 



Distribution of Sphceraphides. — For the above reasons the 

 sphseraphides may often escape detection, as was the case in my 

 first examination of plants belonging to the order Caryophyl- 

 lacese, in which the individual crystals are commonly minute or 

 obscure, and yet are regularly present in more or less abundance, 

 either separately or aggregated into sphseraphides. In some 

 species of this order {Silene Armeria for instance) the crystals 

 are larger, and compose such very distinct sphseraphides as to 

 aflbrd good subjects for preliminary examinations ; for though 

 these sphseraphides vary much in size, numbers of them are 

 about YTTtToth of an inch in diameter. They are most irregu- 

 larly scattered through the tissues of the plant. The diffusion 

 of sphseraphides throughout Ptfanerogamia, especially in the 

 leaves, and parts which are modifications of leaves, is so exten- 

 sive that I have never failed to find them in a single species of 

 of the orders Caryophyllacese, Geraniacese, Paronychiacese, Ly- 

 thracese, Saxifragacese, and Urticacese, and believe that few, if 

 any, orders could be named in which sphseraphides do not exist 

 as part and parcel of the healthy and growing structure of the 

 plant. Hence it would require a very extended series of obser- 

 vations to determine how far the sphseraphides might be available 

 as botanical characters. 



Sphceraphid-Tissue. — In some cases the sphseraphides, far 

 from being very variable in size, and scattered without order 



